4. Oxidation and phosphorylation of each glyceraldehyde 3-phosphate produces 1,3-biphosphoglycerate with a high-energy phosphate bond (wavy red line) and NADH.
5. Through substrate-level phosphorylation, the high-energy phosphate is removed from each 1,3-biphosphoglycerate and transferred to ADP forming ATP and 3-phosphoglycerate.
6. Each 3-phosphoglycerate is oxidized to form a molecule of phosphoenolpyruvate with a high-energy phosphate bond.
7. Through substrate-level phosphorylation, the high-energy phosphate is removed from each phosphoenolpyruvate and transferred to ADP forming ATP and pyruvate.

In summary, one molecule of glucose produces two net ATPs (two ATPs were used at the beginning; four ATPs were produced through substrate-level phosphorylation), two molecules of NADH + 2H⁺, and two molecules of pyruvate.

During aerobic respiration, the two pyruvates enter the transition reaction (see Fig. 13) to produce two NADH, two CO₂, and two molecules of acetyl-CoA. The two acetyl-CoA then enter the citric acid cycle (see Fig. 17) to be further broken down. During the transition reaction and the citric acid cycle, the molecules of NADH and FADH₂ produced provide hydrogen ions and electrons to the electron transport system for chemiosmotic phosphorylation (see Fig. 28) and further ATP production.

During fermentation, the pyruvates are converted to some fermentation end product (such as lactate or alcohol and carbon dioxide) without further ATP production.

Last updated: Feb., 2021
Please send comments and inquiries to Dr. Gary Kaiser